Why are there 'gaps' in the Loft

With lots of help from the forum* I have managed to get the below script (attached): creating a helical stair based on a custom footprint. I am using an Adaptive Component (attached) placed on points along the helix, which I want to ‘Loft’ to create a solid or polysurface (Sweep won’t work as the underside has varying angles).

All seems to be working fine but I don’t understand why there are gaps in the Loft? I understand that it has something to do with the Chop.List node. I understood that the “Chop.List” node is required to define when the correct number of placement points is reached. However it seems to also ‘chop’ the loft function.
Strangely I am able to create a more continuous Loft by slowly increasing the “chop number” and re-run the script each time.

Can someone explain/ help me?
Thanks a lot.

Adaptive Component 8 Point.rfa (340 KB)
Helical Stair 180806-2.dyn (281.4 KB)

Hi @philipp_lammers,

I guess you are just lacking at the beginning of each sublist the point at the end of the previous one. I think you actually want to do something of that type :

Hope that helps

*edit : chaged the example

By having a quick look it seems as the null values further down your list mix up things a little bit. Below a little screenshot of some “washing”, should probably be done a way up in your script. Can’t get the loft surface node to work, but lofting as solid seems to do the trick.


Thank you both for your advise.
I had a look at both of your suggestions but - maybe I misunderstand - they seem to be not the answer.

@mellouze I don’t need to add the previous points to it. Each of the sub-lists (containing the 8 points) is exactly what I need to place the 8-point Adaptive Component. If I “shift” the values of the list by adding the “last” as the “first” the placement order of the A.C. doesn’t match.

@jostein_olsen I think the “null” values were the cause for another problem I had with the original script: at the top of the stair were some points left over. However, since posting the Design Brief for the stair has changed, resulting in a slightly different setup (see below). This comes with a whole lot of new issues.

The issue of gaps remains - I found a workaround by creating a “final” geometry using Revit’s own “Create Volume” function.

Helical Stair non-perfect 180808-4.dyn (258.0 KB)

You may be wrong, if the suggestion below is what you want :expressionless:

This is obtained by replacing List.Chop with List.Sublists
Helical Stair 180808-1.dyn (295.9 KB) (ver 2)


Thanks @Vikram_Subbaiah.

I was sure that I simply didn’t understand how it would work - I wouldn’t question the wisdom of the Forum.
Your amendment is a great help and I ‘think’ I now understand how it works. Still so much to learn.

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